public class MySingleList implements IList{
//内部类
    static class ListNode {
        public int val;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }

    public ListNode head;

    public void createList() {
        ListNode node1 = new ListNode(12);
        ListNode node2 = new ListNode(23);
        ListNode node3 = new ListNode(34);
        ListNode node4 = new ListNode(45);
        ListNode node5 = new ListNode(56);

        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;
        node5.next = null;
        this.head = node1;
    }

    @Override
    public void display() {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println("");
    }

    @Override
    public int size() {
        int len = 0;
        ListNode cur = head;
        while (cur.next != null) {
            cur = cur.next;
            len++;
        }
        return len;
    }

    @Override
    public boolean contains(int key) {
//        if(head.val == key) {
//            return ;
//        }
        ListNode cur = head;
        while (cur.next != null) {
            if (cur.val == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public void addFirst(int data) {
        ListNode node = new ListNode(data);//实例化
        node.next = head;
        head = node;
    }

    @Override
    public void addLast(int data) {
        ListNode node = new ListNode(data);//实例化
        if(head == null) {
            head = node;
            return;
        }
        ListNode cur = head;
        while (cur.next != null) {
            cur = cur.next;
        }
        cur.next = node;

    }

    @Override
    public void addIndex(int index, int data) {
        int len = size();
        if (index < 0 || index > len) {
            System.out.println("index位置不合法");
            return;
        }

        if (index == 0) {
            addFirst(data);
            return;

        }
        if (index == len) {
            addLast(data);
            return;

        }

        //从中间插入
        ListNode cur = head;
        while (index-1 != 0) {
            cur = cur.next;
            index--;
        }
        ListNode node = new ListNode(data);
        node.next = cur.next;
        cur.next = node;
    }

    @Override
    public void remove(int key) {
        if (head == null) {
            return;
        }
        if (head.val == key) {
            head = head.next;
            return;
        }

        ListNode cur = findNodeOfKey(key);
        if (cur == null) {
            return;
        }
        ListNode del = cur.next;
        cur.next = del.next;

    }

    public ListNode findNodeOfKey(int key) {
        ListNode cur = head;
        while (cur.next != null) {
            if (cur.next.val == key) {
                return cur;
            }
            cur = cur.next;
        }
        return null;
    }

    @Override
    public void removeAllKey(int key) {
        if (head == null) {
            return;
        }
        if (head.val == key) {
            head = head.next;
        }
        ListNode cur = head.next;
        ListNode prev = head;
        while (cur != null) {
            if (cur.val == key) {
                prev.next = cur.next;
                cur = cur.next;
            } else {
//                prev = cur;
                cur = cur.next;
                prev = prev.next;
            }
        }

    }



    @Override
    public void clear() {
        ListNode cur = head;

        while (cur !=  null) {
            ListNode curN = cur.next;
            cur.next = null;
            cur = curN;
        }
        head = null;
    }



    //尾插
//    public void addlist(int data) {
//        ListNode node = new ListNode(data);
//        if(head == null) {
//            cur.next = node;
//            return;
//        }
//        ListNode cur = head;
//        while (cur.next != null) {
//            cur = cur.next;
//        }
//        cur.next = node;
//    }

    public boolean hasCycle(ListNode head) {
        ListNode fast = head;
        ListNode slow = head;

        while (fast != null && fast.next != null) {
            fast = fast.next.next;
            slow = slow.next;
            if(fast == slow) {
                return true;
            }

        }
        return false;
    }








}
